The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, hybrid vehicles or electric vehicles, which are called environmentally-friendly vehicles, may generate driving power by an electric motor (hereafter, also referred to as a “driving motor”) gaining torque from electric energy.
For example, hybrid vehicles travel in an EV (Electric vehicle) mode, which is a pure electric vehicle mode using only the power from a driving motor, or travel in an HEV (Hybrid Electric Vehicle) mode using torque from both of an engine and a driving motor as power. Common electric vehicles travel using torque from a driving motor as power.
Most of the driving motors used for the environmentally-friendly vehicles are PMSMs (Permanent Magnet Synchronous Motor). The PMSMs require to improve the performance of the permanent magnet in order to achieve the enhanced performance under a limited layout condition.
Neodymium (Nd) in the permanent magnet improves the intensity of the permanent magnet and the dysprosium (Dy) improves demagnetization. However, these rare earth metal elements (Nd and Dy) in the permanent magnet are buried under the ground in a limited countries such as China. Thus, the price is very high and frequently fluctuating.
In order to improve those problems, an induction motor has been recently examined, but there are limitations of excessive increase in volume, weight, and size for achieve the same motor performance.
On the other hand, the WRSM that will replace the PMSM has been developed more recently as a driving motor that is used as a power source for environmentally-friendly vehicles.
The WRSM is replaced to the PMSM by electromagnetizing the rotor when applying current by winding a coil around the rotor as well as the stator.
In the WRSM, the rotor is disposed inside a stator with a predetermined gap. A magnetic field is generated when power is applied to the coils of the stator and the rotor, and the rotator is rotated by a magnetic action generated between the stator and the rotor.
Meanwhile, the WRSM winds coils around the rotator, unlike the PMSM. Accordingly, a large centrifugal force is applied to the rotor coil when the rotor rotates by a high speed (above maximum 10,000 rpm in case of usual EV).
Accordingly, in the WRSM, arrangement of the rotor coil is deteriorated or separated by a centrifugal force applied to the rotor coil during the high speed rotation of the rotor, and the rotor core may be damaged due to the concentration to the rotor core around which the rotor coil is wound.
Therefore, mechanical strength supporting a centrifugal force of the rotor coil is gained by inserting a wedge between tee and tee of the rotor core in a conventional art. However, the number of component increases with this conventional method
On the other hand, a rotor coil is wound around a bobbin using a nozzle-type winding device after the bobbin is assembled to tee of the rotor of the WRSM in the conventional art.
In the conventional art, since the rotor tees are integrally formed at the rotor core, difficulty in the process arises when the rotor coil is wound around the bobbin by using the nozzle-type winding device. This results in the deterioration of a winding space factor, thereby increasing a copper loss of the motor.